System op speed control foe



BEST AVAILABLE COP.

M i Q 1 1927. 1,619,673

a ch HULL SYSTEM OF SPEED CONTROL FOR INDUCTION MOTORS Filed Sept. 10, 1923 2 Sheets-Sheet l In /entOr-':

John I.Hu||, y His 1413 'orney.

1,619,673 J. I. HULL SYSTEM OF SPEED CONTROL FOR INDUCTION MOTORS v March 1 1927 BEST AVAILABLE COP.

Filed Sept. 10. 1923 2. Sheets-Sheet 2 FQAZ. I a

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/V-POLE E IMPROVED ZN- P015 R z/v-Pui Invent-low:

BIN/6H swmnwwv John IHull His Abborh es.

Patented Mar. 1, 1927.

" H D. TA E- BEST AVAILABLE cop 1,619,573 ATE T OFFIC .TOHN I. HULL, F SCHENECTADY, NEW YORK, AssIGNon TO GENERAL ELECTRIC com- YANY'f, A CORPORATION on NEW YORK. I

SYSTEM QF'SPEED CONTROL ronixunuorron morons.

Application filed September 10,1823. 4 Serial No. 661,768.

My invention relates to systems of speed control for induction motors and especially to improvements in speed. control. systems. wherein a polyphase commutator machine is concatenated with a load motor for the pur-- pose of regulating its speed over a range including subsynchronous, synchronous and supersynchronousspeeds.I 7

It is wellknown that the, spe ed of an -.in-;h. ction; motor may-be readily and cconomically controlled, by regulating the field ot-a commutatonmachine which is con-- nected in;cascade, or concatenated, with it. As pointed-out in my: Patent No. 1,306,594. -:granted June 10,-;1919, it the shuntfield;

winding of-the,commutatorgmachme: has impressed upon it -ahvoltage ofload motor slip frequency,,obta ined-from the mam mo? to); collector-. rings;,t-helphase and magni- 2012 tude of the shunt; field; flux and therefore.- ii has a ii na we n. h Qm ta i;- machine. voltage and that of -the-load motor secondaryfflwinding; varies, because of; the; shuntiie ld inductance the .speed of 1 the Z 2-' .E]( a;d.motoris changed',. and; the operation; of z the; induction motor is therebyrendered- --and .imcertain -at .speeds in the n stable.

113 a l w i s arce Qt; P w r. fo e ng he i ln a fi d in e -gqfi th omm a mama are; #1193 i i tor in. eq en y-n ay ng'qn componen Wi g .for ve m-z ing. .th eactarrce ldrop oi; the, shunt field Q' i-edi ice he lue ifimhi z iiimpq t a 3' 3i Q-.,-:th s da itti eqee vy {and ndu d: mega @Mmethea pemp en afonl' a oinin h s ce d op. f h s n fi ld; winding the value of whichis-independent of theload motor; slip voltage, eithe r v the 4auroiin'ionent voltages applied to the shuntfield. or its reactance and resistance being independentlyadjustable. lnthe past, control offthe componentvoltages in the manner indicated has involved the use of an z'autot-ransformer with taps and an adjustable ;rheos tat together with a set of contactors and a master controller or other switch-' ing means vfor changing theadjustment to varythe speed of the load motor,. all of. -v.'hich'increases the cost and complexity ofthe. ('(mtrol apparatus. .In accordance with my present invention the component voltages: applied to the shunt field winding of theronimntator machine are automatically as regulated by a single exciting machine and the use of a transformer and rheostat together with the control apparatus incident theretois voided. s 1

An object of my invention is to provide meansi'or regulating the speed of an- 'induction. motor in a simple and effective 1nanner.-

A further object is to provide an: excit ing machine arranged to produce theficonnponent voltages required to properly excite a polyphase commutator regulating machine concatenated with an induction motordlfor' the purpose of controllingits'speed qA further object is to. provide an improved: polyphaseexciting machinez- E: Myinvention will be better .under'stoodfrom the following description taken'in con-= nection with the accompanying drawing and its scopewill be pointed 'outinth'e appended claims: ;f 4

- in vii-1'- Refenring now to the-drawing,

Fig;= 1'.' shows an induction motor: speed control systemin: which 'an -excitingazinachineuon structed in accordance with fmyninvent-ion' has been embodied .Figfi 2' shows a r'nodi-ai 801 fied form of eXcitin g machine Fig:z3 sh'dws' the re ation of the voltage-impressed Yonathe 5 field of the regulating machine to the sepa i ration of the i exeiter brushes; ':and -i'g; shows a modified-r form ioii staton E strnptnre suitable; ion use on; i the *enhite'rr s'liov'vni iri Fig.2; "-'=.'Ii r=. draw .5 nil-l ,l ig l ishows an. adjustable speed; IN-poleinduction l motor i-l; the;- primary windin -=of}' which 1.,i s; interconnectecbwith a polyp ase QR Q f: POWQIE 2 and the; secondary wirid g: f hich. is connectedatofith'e slip irings'i -m l 0n 'the-shaft-e. ofthe motop' 1'52 A so mounted-- on the. .shaft 4: is an exciting machine 5- provided .-with' an. N-ipole' poly 'los phasegvinding 6 arranged to-he-conductively'associated with the source Q-thiough slip 1'ings -'i", swit-ch- 8, and adjustable transformer- 9. Upon. thestatorof .theexciter 5 is wound a 2- N-pole polyphasewinding-'lfirariranged to be connected with the 'secondarywind ing ofthe motor. 1 through I switch 17 'and' slip rings 3. -The exciter- 5: is. further-pro vided with a commutated winding10 ar-- ranged to rotate with the winding 6 andinterconnected with the'shu'nt field windilig ll of-a regulating machine 12 for thefpur- .poseot' supplying thereto excitingcurrent 2 ot'slip frequency, th'e'winding'lO being in f ductively related to both windings 6 and 16 13:71.35; :14w-14=';and l:.151:can= have :i'm-' pressed;- onethem simultaneously one coinpbnentwoltage :of. load motion-slip zfrequency duotoztbezrotatil'lg' field se'tnip by the N-pole. winding a itinother oo mponent voltage of like frequency due tothrotatingifield .set. up-

by' the, 2 lilpole winding zthe relative values- 1 exc ting a hfti i gulatingnmaohm 5 such: i

-Mmln'gg; the aogitiqia t of -;thej war-ions.

slll ldles' llllibl l hqsimbfi iShQW r -F g 2i: 1; the loaa motor llmayebe, started from-rest 'by glgsing; the switch- ;22; Fwith the ,resistor Linsmm @iQl Q ntrhduceomaiiimum rcsisteneeninwgithe rcQQOJldMWmiirduit. The 19mm EQQlGli'fiC-flfilttfiffii (bye, gradually:- redyeingqthe I secondary-Z: resistance: 1-When a tesulti ggfmm :Short air an-11 slip rings 3 by cutting out the resistor 21.11am been jreachedmthes regulating-machine '12 hayingbeen previously-brought :up to speed; the, scivitch -lT;-is ,olosed,-the'z'switch 22 is opened andi switoh 8.51s closed; thereby energizi-ngiithe ericiting iwiiidings lti and '6 or" the -machine i5taaUnder 'theseficonditions the exciterhbru'shes of i'eachI-phase which-have beenvpreviously st onl equipotent-ial points forz-ebothw-N and '-2 fN pole swill "have no voltagei set -upjbetweenj them' {and consequen'tly'no. yolta'ge is impressed on the slum t' Winding. l lpoffthe machine- 12." The load motorili-willnowop'era'te'asia 'no-rnial induction motor haying' its secondary winding connected to the lo-w "r'esistanc'e" armature circuit "*of the regulating 'inachine 12. If

I the brushes "connected"to the-beginning of each phase of Winding 11 be'now moved in one direction-aroundflt-he excitei-"commutator while those connected to-the. fends of each plia'se ;be moved in the 'opposit'e direction, component"voltages' induced by the flux of the-N tindflfidlpble windings respect-irely Gill beset up between them and the resultant of these component roltages ivill be impressed on the shunt field'ninding 11 These 5 component 'i 'olt agesfmay'be'arranged to have any-desired'phas elatioiifivith respect to one another' or ti i r spcitTto other voltages oi. currents in the ciijhitjfhis n'1'i1y be accomplished the e zciter stator. by

' shifting. all the bru; es tojan'y desired deeyz s nt ease .;znotmahand is l p BEST AVAlLABLE COP 8-- gree in the same direction beforeor' after or during the process of shifting inopposite directions, by shifting the brushes in opposite directions'at different rates ,of sh ft, by changingthe phase of the voltage applied to the collector rings 7- in any of the va-' rious well known Ways; by shiftingfithe' phase of-the exciter statorxexcitationlsup-i plied through-the Winding l6or iniany other well known manner. Thecomponent'woka age produced by the N -pole windinggfi inayz thus be utilized to balance the'ohm'io dropio'f' the shunt field :11, "and" the component -='pro'-g duced by thec2 N-polewinding l'fi mayrlbe: utilized to balance its \reactanc'e' drop. -=As= 805 a result of the adjustment of the bnushesithe speed of the inotorwill be chan'ged 'ih a well known manner and bysimiIaP-adjustm'ents the :motor: may be 'madeto operate at anyother .desird speed.- I i-Wk; "1'"- The transformer 9 may be-r-adj uste'd to control the" Voltage. applied to=-tl1e' *N-pole winding 6 both as to phase-and 1ml'gnitufgl'e' and'fit'desir'ed a similartrensformer inay 90 be inse'rtedin the leadswhich the 2 Nqgbl'ej 1 Winding is interconnected With' the {secondary Winding of the load-motors The excit''rj is shown as fixedto 'rotate' with the sh" of the load motor 1.: 'lt is of cg'iur'se ob t-i 95 that the exciting machine may berdriven by} any suitable means "for mziintaini'n g it "in exact synchronous r relation" with" the" ii'i'air'i motor and that the number of-feiiciter 'ptil's need not be' the same 'as 'thatbfthe mfihif 10o motor'provided the propefspe'ed' rl is inainteinedbetween the two machines.

'Fig. 2 shows a modified forin"ofjexciting machine having certain desirable if efitu'i not shown on the exciter fi shoitnhn ,1? The exciter' 5 is-illustrated as a t pol giole, machine with half of the brushes omitted. 'lhe eXc-itcr 25 is provided With al pole rotoro Winding 26 interconnected with the phase-'lineZ and ainodified form of l pole stator Winding 27 adapted to fbeintercon i nected with the secondary winding oijt-h ei main motor 1. (See 1;) The. winding" 27 is concentrated in 'zones QSJ'Sparatedf as illustrated by zones 29 inwhich' no gogi; tizing force will be exerted; The mind ng-s 26 and 27 are non-inductively arranged with respect'to each other buta reQbothj induci tively associated with a commutator-i riding-30 adapted to cooperate ivithbi'ushes fil and 32 arranged to beshiited'infopposite directions by means of ahand ivhe el; and pinion 34 which nieslieswith 'racksfifiaiid- 36 of the brush supporting structures fi'i 38 respectively. VVhen 'the' f b ruslie'si sl ightly separated under a' one no fi-"olt; age is impressed on them by the statorn inding 27.: As they are separated,furthe and, pass under the zones 28 'f-heyfwill p ck; up Yolta es'a'sindicated in Fig. 3.- 1 l 130 the zones 27.

.35; cordance; with the patent statutes.

In Fig. 3 the .distance between brushes connected to opposite ends of the phases-0t the winding 11 are plotted as abscissae and the voltage between these brushes are plotted as ordinates. Thus the curve labeled N-pole shows the voltage impressed on the brushes due to either the winding 6 of Fig. 101- the winding 26 otFig. 2, the curve labeled 2 N-pole shows the voltage impressed on the brushes due to the distributed winding 16 of Fig. 1, and the curve labeled Improved 2 N-pole shows thevoltage impressed on the brushes 31 and 32 of Fig. 2 due to the concentrated winding 27. The curve labeled Improved 2 N-pole may be made to assume the form indicated by the dotted line A in Fig. 3 it the stator winding 27 is arranged, as shown in Fig. 4, not in twoslots but in two or more slotsin By increasing the number of slots on one. side of the windingthe curve may thus be -made to. approximate almost any desired form.

I- have explainedzmy invention bv illus- 'trating and describing certain SPECJfiC embodiments; thereof, but it will/be readily un'-' derstood by those skilled in the art that the.

invention may be embodied in many other forms-than those shown and-described. I, accordingly, do not wish. to be restricted .to-

the particular forms or constructions dist. closed herein by way of example for the purposeotsetting forth: my invention'in ac- The terms of the appended 1 cl aims,- .are,; therefore, not restricted. to the precise .structures disclosed, but are :intende'dto cover. all changes and .modificationsawithin thespirit "and;

scope of my invention.;'

What I laimas new and; desirerto secureby Letters Patent of theUnitedr States, is

1. Av system ;of speed, control wherein -,an induction motor arranged to be supplied with current troma suitable-source of power;

is concatenated; with a regulating machine:

provided with. a shunt. field r winding, and wherein a voltage of:the same frequency; :as-

that of ,the 'slip current of :said induction motor is impressed ,onfsaid shunt field-wind:- ing andis varied to control the .spee-d'o'f said induction motor, ,c haracteriz ed .by the fact that a macl irie provide d for exciting said wlnding 18 arranged to-generate independently adjustable component voltages which are substantially. proportional, to theshunt field ohmic and reactive drops respectively. 2.;Asyste n of speed control wherein an induction motor arranged to be supplied with current from a suitable source of power is concatenatedwith a regulating machine provided with.a shunt field winding and wherein a voltage ofthe same; frequency as. that of the slip current ofsaid induction inotor is impressed on said .shunt field winding and is variedto control the speed of said BEST AVAILABLE COP.

a eommutated winding inductively relatedto said exciting windings and arranged to supplycurrent to said shunt =fieldwinding.

3'. A system of speed control wherein an induction motor arranged-tob'e supplied with current from a suitable source of power is concatenated with a regulatingmachine provided with a shunt field winding and wherein a voltage of "the same frequency as that of the slip current of said induction motor is impressedodsaid-shuntfield winding and -is variedtolcontrol"thespeed of said induction motor, comprising =a'n exciting machine provided with' a polyphase ex citing windingarranged to be interconnected with-the secondary-winding of said induction motor, a second poly'phase exeiting winding non-inductively related to said first -mentioned exciting winding .and arranged to be intercon'nected'with said source of power, and a commuta-ted winding inductively related-to bothsaid exciting windings Endd arranged to supply current=to said shunt el.-.- 4. A system of speed control wherein' an induction motorarranged t-o-ibe supplied with current from a suitable son-rceof power is concatenated with 'a regulating machine provided with ,a'sliunt field winding "and wherein a ivoltageiof the. same trequency 'as' that :ot; theslip current of said induction motor is impresd} on: said: shunt field winding and is variedtocontrol the; speed oi-said induction motor,: comprising anv exciting ma chine provided with; an' -N-pole .zexciting winding arranged; to be interconnected with said ,source of ,power, a-2Nwpole :exciting winding. arrangedto be interconnected with: the secondary winding ofsaid. induction motor, and a commutated windinginductively related with said N-poleand2N pole emit-- ing windings and arranged-.tmsupply current tosaid shunt .field;winding.--

5. A system of: speedicontrol wherein an induction motor. arranged gtobe supplied with current from a suitablesource ofppower is concatenated with ,a regulating -machine provided with. a shunt field winding and wherein a voltageof thesame frequency as that of the slip current of said induction mo-- tor is impressed on said shunt field winding and is varied to control the speedof said induction motor, comprising a polyphase exciter provided with-an. N-pole rotor winding arranged to be interconnected with said source of power, a ZN-pole stator winding noninductively related to said'N-pole winding and arranged to be interconnected with the secondary winding of said induction motor, and a polyp 221296 commutated winding inductively related to said N-pole and QN-pole windings and arranged to supply currentto said shunt field winding.

6. A system of speed control wherein an induction motor arranged to be supplied with current from a suitabie source or". power is concatenated with a regulating machine provided with a shunt. field winding an, wherein a voltage of the same frequency as that of the slip current of said induction motor is impressed on said shunt field winding" and is varied to control the speed oi said. induction motor, comprising a polyphase exciting machine provided with an N-pole rotor winding connected to have its phase se quence in a direction opposite to that in which said exciting machine is driven and arranged to be interconnected with said source of power, a QN-pole stator winding connected to have its phase sequence in the same direction as that which said erator is driven and arranged to be interconnected with the secondary winding of said induction motor, said N-pole and QN-pole windings being non-inductively related to each other and a polyphase commutated winding inductively related to said N-pole and QN-pole windings for supplying to said shunt field winding current of the same frequency as that of the slip current of said induction motor.

7. A system of speed control wherein an induction motor arranged to be supplied with current from a suitable source of power is concatenated with a regulating machine provided with a shunt field winding and wherein a voltage of the same frequency as that of the slip current of said induction motor is impressed on said shunt field winding and is varied to control the speed of said induction motor, comprising an exciting machine provided with a polyphasc exciting winding arranged to he interconnected with the secondary winding of said induction motor, a second polyphase exciting winding arranged to be interconnected with said source of power, a conunutated winding inductively related to said exciting windings, brushes associated with the opposite ends of the dif- SEST AVAlLABLE COP 5 "t'ei'ent phases oi said shunt field winding, and means -i'or shifting the brushes associated with opposite ends of each phase of said shunt field winding in opposite directions whereby the voltage impressed on said shunt field winding may be varied.

A system of speed control wherein an induction motor arranged to be supplied with current from a suitable source of power is concatenated with a regulating machine provided with a shunt. field winding and wherein a voltage of the same frequency as that of the slip current of said induction motor is impressed on said shunt field winding and is vari d to control the speed of said induction motor, comprising an exciting machine provided with a polyphase exciting winding to be interconnected with the sec ondary winding of said induction motor, a second polyphase exciting winding non-inductively related to said first mentioned exciting winding and arranged to be interconnected with said source of power, a commutated winding inductively related to said. exciting windings, brushes associated with the opposite ends of the different phases of said shunt field winding, and means for shifting the brushes associated with opposite ends of each phase of said shunt field winding in opposite directions whereby the voltage impressed on said shunt field winding may be varied.

9. A system of speed control wherein an induction motor arranged to be supplied with current from a-suitable source of power is concatenated with a regulating machine provided with a shunt field winding and wherein a voltage of the same frequency as that of the slip current of said induction motor is impressed on said shunt field winding and is varied to control the speed of said induction motor, characterized by the fact that a machine interconnected with said source of power and the secondary winding of said induction motor is provided with brushes arranged to be shifted to regulate the component voltages impressed on said shunt. field winding.

In witness whereof, I have hereunto set my hand this 8th day of September, 1923.

JOHN T. HULL.

Jill) 

